I am unable to save after editing from 2.4.3 (r4533) on Mac OSX 10.5.6 because of the above error, yet I always make cuts at I frames (using the double arrow buttons to move the edit point) and the display always shows an I frame (at the moment it's reading Frame Type: I (00) as the start of my video). I have no filters selected and have chosen 'Copy' for both Video and Audio content.

Any suggestions most welcome.

Many thanks - GeoffT.

Not the start of your video needs to be an I-Frame (that's always the case), the A-Marker must be set on an I-Frame!

Thanks for the reply. Sadly it makes no difference. I tried setting the A marker to the beginning of the file (which as you say is an I frame) and to another I frame in the file but the result is the same: 'The beginning frame is not a key frame. Please move the A marker.'

GeoffT.

If your first frame is not an I-frame use the "double forward arrow" to skip to an I-frame. Move one frame back (single arrow). Click on B for B-frame. Select (menu) Edit->Cut to remove the first few frames.
Now your first frame is an I-frame.

I have the same problem, the frame IS an I frame. I can advance to a future iframe as well, and set the A marker there, same result when trying to "copy" a m2ts input file containing H.264 to mkv output. Simply want to change containers.

No matter what I do, the error comes up and I cannot save mkv.

using the >> arrows, you probably keep landing on the wrong type of frame, regardless of what it shows in the preview.

I was having the same problem, but found that if i navigate manually with mouse when choosing the (A) inpoint rather than using the arrows, it lands on a frame that is usuable.

It'll be harder to have a precise in point, but it works everytime, and the >> arrows failed everytime.

Sometimes I have found that this still didn't work and I had to clear the edit points several times before it did work. I think that command is under the EDIT tab at the top. Or if that still didn't work I would exit the app and start it again.

Hope is the trap the world sets for you every night when you go to sleep and the only reason you have to get up in the morning is the hope that this day, things will get better... But they never do, do they?

I will post the solution to this problem so other people who don't know can resolve it:

In fact you have to use the [A Marker always first... This problem only appear when you have to use the B] Marker.

I was having this problem for cutting the video from the beginning to the middle (for me to have just the last part of the video).

So when using the B] Marker, that's what I do:

-When on the image 0 (beginning of the video), Click the forward single arrow just to move to 1 image forward. (if you don't have to cut from the beginning, just place the [A marker where you want)-Then use the [A Marker-Then go to where you want to put your B] Marker, and use the B] Marker-Then cut the part and save the video to whatever format you want.

This way no more frame errors problems.

Edit: This solution does not work with the latest version 2.6.1, I use the 2.5.6

Don't use the left or right arrow keys but instead use the UP and DOWN arrows. UP and DOWN goes through key frames which you have to use to make your cuts. Using left and right will not do this and you will have an error.
Works with Avidemux 2.6.7

No problem. Commercials at beginning and end removed, no re-encoding. Try a smart-rendering editor. I used TMPGEnc Smart Renderer v4 . Attached is an edit of the low-bitrate UTube version. It worked on the bigger version as well.

Do I have to set A to the first i-frame of what I want to keep, or is every frame ok? (I know predicton for upcoming frames is done by the frame before and that should be an i-frame, but how come my videos that I started and stopped with a B-frame do play ok?)
Does B have to sit at the i-frame of the scene that I want to stop the clip with?
Will the frame that I set B to be the last visible in the resulting clip or is it marking the first frame that should not be included in what I want to keep? (in other words: do I tell avidemus to keep the frame that lies ON B or not keep it and stop the clip before that exact frame?)

PS: also, when I have clips that are named 1, 2, 3, 4,... of one movie (only broken in part by the PVR to fit FAT32 I guess), Avidemus asks me, if I want to append all following clips. If I click yes, some don't get appended or mixed in order. OS X 10.9 and Avidemus 2.6.6app

Do I have to set A to the first i-frame of what I want to keep, or is every frame ok? (I know predicton for upcoming frames is done by the frame before and that should be an i-frame, but how come my videos that I started and stopped with a B-frame do play ok?)
Does B have to sit at the i-frame of the scene that I want to stop the clip with?
Will the frame that I set B to be the last visible in the resulting clip or is it marking the first frame that should not be included in what I want to keep? (in other words: do I tell avidemus to keep the frame that lies ON B or not keep it and stop the clip before that exact frame?)

If you set to "copy" then yes, it has to be on I frame boundaries . Easy way to tell is to use the "<<" and ">>" buttons at the bottom of the GUI to navigate when you get close, then set the mark in / mark out. Those "<<" and ">>" buttons will jump to the closest I frame

PS: also, when I have clips that are named 1, 2, 3, 4,... of one movie (only broken in part by the PVR to fit FAT32 I guess), Avidemus asks me, if I want to append all following clips. If I click yes, some don't get appended or mixed in order. OS X 10.9 and Avidemus 2.6.6app

Not sure, are they named with the same number of "place holder" digits?

I now discovered that, if I choose a B-frame or p-frame for A or B that it will jump the markers to the next i-frame automatically in the resulting video. I don't see it jumping there while cutting, only after the copy process is completed.

To the other question, it is only 4 pieces: name1.mts, name2.mts, name3.mts, name4.mts